Field of the Invention
This invention relates to a document control method, and in particular, it relates to a method that controls the copying and scanning of a hardcopy document to prevent unauthorized copy and scan while allowing authorized users to obtain high quality copies.
Description of Related Art
Technologies exist for preventing unauthorized copying of a hardcopy document. In one such technology, sometimes referred to as “copy guard” or embedded pattern printing, a security pattern, such as a dot pattern or a pattern using other fine symbols, is embedded as background in the hardcopy document (referred to as a first generation copy here). The security pattern is inconspicuous in the first generation copy, but when the first generation copy is photocopied, the security pattern becomes conspicuous. The conspicuous security pattern typically depicts a warning message such as “Do Not Copy,” “Void,” etc. Some such technology will prevent unauthorized users from making a photocopy at all (e.g., the copy machine is equipped with software that detects certain security patterns), and even when an authorized user is allowed to make a photocopy (e.g. by entering a password), the resulting hardcopy (referred to as a second generation copy here) will still bear the conspicuous security pattern.
Digital rights management (DRM) is a technology used to control access to DRM-protected documents in electronic or hardcopy form. A DRM system typically uses a digital rights management server (DRM server or RMS server) that stores information regarding the protected documents and users of the system, for example, which users have what kind of permission to access which document, in a DRM database. The RMS server can communicate with client computers, printers, scanners, copiers or multi-function devices to perform digital rights management.